For example, Technique disclosed in Patent Citation 1 is known. According to this technique, a storage system includes a controller and a plurality of JBOD (Just a Bunch Of Disks) devices. Each of the JBOD devices includes a plurality of HDDs (Hard Disk Drives) which are connected by a loop, a SES (SCSI (Small Computer System Interface) Enclosure Service) function unit, and an ID setting unit.
If a JBOD device is additionally provided, the ID setting unit within this additionally provided JBOD device allocates an ID to each HDD within this JBOD device. And the SES function unit within this additionally provided JBOD device performs a comparison to see whether the ID which have been sent from the controller and the ID which has been allocated from the ID setting unit to the HDD agree with one another or not. If these IDs do not agree with one another, then this HDD to which ID have been allocated which do not agree are disconnected from the loop.